4.1 Compacted asphalt mixture specimens molded by this procedure are used for various physical tests such as stability, flow, indirect tensile strength, fatigue, creep, and modulus. Density and void analysis are also conducted on specimens for mixture design and evaluation of field compaction.

Note 1: Uncompacted mixtures are used for determination of theoretical maximum specific gravity.

Note 2: The quality of the results produced by this practice are dependent on the competence of the personnel performing the procedure and the capability, calibration, and maintenance of the equipment used. Agencies that meet the criteria of Specification D3666 are generally considered capable of competent and objective testing, sampling, inspection, etc. Users of this practice are cautioned that compliance with Specification D3666 alone does not completely ensure reliable results. Reliable results depend on many factors; following the suggestions of Specification D3666 or some similar acceptable guideline provides a means of evaluating and controlling some of those factors.

1.1 This practice covers preparation and compaction of 4 in. (101.6 mm) diameter by nominal 2.5 in. (63.5 mm) high cylindrical asphalt paving mixture specimens. This practice is intended for use with laboratory and plant-produced asphalt mixtures with aggregate up to 1 in. (25.4 mm) maximum size and for recompaction of asphalt paving mixture samples.

1.2 There are three types of Marshall compaction apparatus in use. The following types of hammer arrangements are included in this practice:

1.2.1 Manually held hammer handle is attached to a flat compaction foot through a spring-loaded swivel and is hand operated (original standard developed by the United States Army Corps of Engineers).

1.2.2 Hammer handle restrained laterally (fixed) but not vertically, attached to a flat compaction foot through a spring-loaded swivel and is either mechanically or hand operated. There may or may not be a constant surcharge on top of the hammer handle. Mechanical hammers are available that operate at (1) nominal 55 blows per minute or (2) equal to or greater than 75 blows per minute.

1.2.3 Hammer handle restrained laterally (fixed) with constant surcharge on top of hammer, is attached to a slanted compaction foot on a rotating mold base, and is mechanically operated. This method must be used as a referee method.

1.3 Although the mass and height of mass drop for each apparatus are the same, density achieved in compacted specimens with the same number of blows will be different. It is up to the owner or specifier to establish the specific required number of blows to be used for compaction of the specimen in relation to the field.

1.4 Units—The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.

1.5 The text of this standard references notes and footnotes which provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of the standard.